The overall objectives of this project are to identify and solve the technical and neurobiological problems associated with the creation in cell culture of two-dimensional, ordered neuronal networks of over 30 nerve cells in which all interconnections are known, all neurons can be stimulated, and all major extracellular electrophysiological activity can be monitored for an extended period of time. We are presently developing two new techniques without which the objectives stated above would be unrealistic. These are: (1) the construction and testing of multimicroelectrode surfaces featuring 36 gold conductors photoetched onto a glass plate that serves as the floor of a tissue culture chamber. The central terminals of these conductors are arranged in 6 columns and 6 rows within a 0.5mm x 0.5mm area. A 70 sq. micrometer area on these terminals is deinsulated with a single laser shot; (2) we are also utilizing the laser to manipulate neurons and glia cells in closed chambers under the microscope. Undesired cells can be eliminated and cell processes can be transected with a heretofore unattainable precision and ease. Through the selective elimination of interfering cellular moieties, we plan to create and maintain simple, ordered networks in which the position of all perikarya corresponds to the location of the microelectrode craters and in which the interconnections correspond to a preconceived experimental plan.